DECC$UNIX_LEVEL

   With the DECC$UNIX_LEVEL logical name, you can manage multiple
   C RTL feature logical names at once. By setting a value for
   DECC$UNIX_LEVEL from 1 to 100, you determine the default value
   for groups of feature logical names. The value you set has a
   cumulative effect: the higher the value, the more groups that
   are affected. Setting a value of 20, for example, enables all the
   feature logicals associated with a DECC$UNIX_LEVEL of 20, 10, and
   1.

   The principal logical names affecting UNIX like behavior are
   grouped as follows:

      1    General corrections
      10   Enhancements
      20   UNIX style filenames
      30   UNIX style file attributes
      90   Full UNIX behavior - No concessions to OpenVMS

   Level 30 is appropriate for UNIX like programs such as BASH and
   GNV.

   The DECC$UNIX_LEVEL values and associated groups of affected
   feature logical names are:

   General Corrections          (DECC$UNIX_LEVEL 1)

      DECC$FIXED_LENGTH_SEEK_TO_EOF   1
      DECC$POSIX_SEEK_STREAM_FILE     1
      DECC$SELECT_IGNORES_INVALID_FD  1
      DECC$STRTOL_ERANGE              1
      DECC$VALIDATE_SIGNAL_IN_KILL    1

   General Enhancements        (DECC$UNIX_LEVEL 10)

      DECC$ARGV_PARSE_STYLE           1
      DECC$EFS_CASE_PRESERVE          1
      DECC$STDIO_CTX_EOL              1
      DECC$PIPE_BUFFER_SIZE           4096
      DECC$USE_RAB64                  1

   UNIX style filenames       (DECC$UNIX_LEVEL 20)

      DECC$DISABLE_TO_VMS_LOGNAME_TRANSLATION 1
      DECC$EFS_CHARSET                1
      DECC$FILENAME_UNIX_NO_VERSION   1
      DECC$FILENAME_UNIX_REPORT       1
      DECC$READDIR_DROPDOTNOTYPE      1
      DECC$RENAME_NO_INHERIT          1
      DECC$GLOB_UNIX_STYLE

   UNIX like file attributes     (DECC$UNIX_LEVEL 30)

      DECC$EFS_FILE_TIMESTAMPS        1
      DECC$EXEC_FILEATTR_INHERITANCE  1
      DECC$FILE_OWNER_UNIX            1
      DECC$FILE_PERMISSION_UNIX       1
      DECC$FILE_SHARING               1

   UNIX compliant behavior       (DECC$UNIX_LEVEL 90)

      DECC$FILENAME_UNIX_ONLY         1
      DECC$POSIX_STYLE_UID            1
      DECC$USE_JPI$_CREATOR           1
      DECC$DETACHED_CHILD_PROCESS     1

                                 NOTES

      o  Defining a logical name for an individual feature logical
         supersedes the default value established by DECC$UNIX_
         LEVEL for that feature.

      o  Future revisions of the C RTL may add new feature
         logicals to a given DECC$UNIX_LEVEL. For applications
         that specify that UNIX level, the effect is to enable
         those new feature logicals by default.